Pressure cooker



Nov. 2, 1948. w. A. PLEDGER PRESSURE COOKERV Filed Sept. 29, 1945 INVENToR.

W 1- Uff/r A?. /J 6E@ lBY Nov. 2, 1948. w. A. PLEDGER 2,452,790

PRESSURE CQOKER Filed sept. 29. -1945 s sheetsfsheet 2 l 1U 1g 32 y 22 zo l l 54 A 61 23 34 l I 2/ o l .53 52 I, l 42 o g. I 43 I y 32 44 1 22 A20 34 m y 23 n 54 2/ "D 55 52 5/ .Il c I 43 v y 'l 54 44 59 .0

/X l 34 l ml 54 l1 NVENTOR. M//LL/A 4. PLEDGE/ H/S ATTORNEY Nov.. 2, 1948.

Filed Sept. 29, 1945 W. A. PLEDGER ,PRESSURE GOOKER '3 sheets-sheet s HIS ATTORNEY Patented Nov. 2, 1948 UNITED STATES PATENT @FFME PRESSURE COOKER William A. Pledger, San Francisco, Calif.

Application September 29, 1945, Serial No. 619,324

(Cl. B20-25) 4 Claims.

This invention relates to pressure cookers.

An object of the inventionv is to provide a pressure cooker with a closure, which is easily movable into open and closed positions and is held in tightly closed position by the steam pressurein the cooker.

Another object of the invention is to provide a pressure cooker in which the clamping device for the door or cover of the cooker is coordinated with a valve control mechanism in such a way that the releasing oi the door by said clamp automatically shuts oii the steam supply to the pressure cooker and thereby obviates any danger of scalding or injury from escaping steam.

Another object of the invention is to provide a pressure cooker in which the steam intake and exhaust mechanisms are operated in synchronism, for facilitating the expelling of air, the introduction of steam and the release of the steam from the pressure cooker.

Another object of the invention is to provide a safe and serviceable pressure cooker which may be used in single units or multiple units, which suitably receives trays or the like for the food to be cooked, and which can be easily manipulated for the pressure cooking of food or the like.

The essential features of the invention involved in the carrying out of the objects indicated are susceptible to modification, but a preferred embodiment of the invention is shown in the accompanying drawings, in which:

Fig. 1 is a iront View of my pressure cooker arranged in multiple units;

Fig. 2 is a top plane View of my pressure cooker;

Fig. 3 is a sectional fragmental detail of the connection of the clamp to the valve control shaft;

Fig. 4 is a side view of my cooker;

Fig. 5 is a sectional View of one of the pressure cookers;

Fig. 6 is a somewhat diagrammatic sectional View of the arrangement and control oi the intake and exhaust valves oi the cooker, showing the intake valve fully opened and the exhaust valve closed;

Fig. 7 is a partly sectional and somewhat diagrammatic View showing the connection between the intake valve and the exhaust valve of the cooker, both Valves being in partially .opened position, and

Fig. 8 is a fragmental sectional View of a modified sealing arrangement for lthe door of the cooker.

In. carrying out my invention I make use of a box or casing I which has a closed end 2, sides 3, a top 4, an inclined bottom 6 and a front l.

The bottom 6 as shown is inclined from the front wall 'i toward the closed end 2 downwardly so as to drain condensed steam and the like from the casing I through an exhaust passage 8.

The front end l has an opening S through which the food to be processed is placed into the interior of the cooker casing I. This opening 9 is surrounded by flanges II which extend around the edges of the opening 9 and into the casing I. On the bottom 6 is provided a shelf I2 which has perforations I3 therethrough on which shelf is supported a suitable tray or vessel containing the food to be processed.

A door structure denoted in its entirety by the numeral I4 is provided for the opening 9 at the inner edges of the flanges I I so that the door can be easily moved into and out of operative positions. The door structure includes a door I6 in the form of a segment oi a cylinder. The convex side of this door I6 faces toward the opening 9. Arms I'l extend from the concave side of the door I6 at each end thereof substantially radially with respect to the arc of the door. The arms Il at each end are united in a central hub I8 which latter is formed into an open yoke I9 straddling a stub shaft 2 I. This pivot shaft 2| is flat and the yoke I9 fits slidably thereover. Each shaft 2i is rounded at its outer end and is journaled in the adjacent side 3 of the casing I. One of the shafts 2l extends through one of the walls 3 of said casing I and has a handle 22 on its outer end for the turning of the shaft 2I and thereby turning the yokes I9, hub I8, arms Il and the segmental door I6. The top Wall 4 of the casing I is at such a greater distance from the axis of the shafts 2| than the radius of the convex side of the door IB so as to allow the swinging of the segmental door I5 to an out of way position adjacent said top Wall 4. An abutment 2li on the outside of the side Wall 3 adjacent the handle 22 is so located that the handle 22 rests on it when the door it is open and the overswinging and reversing of the door is thus obviated. The journals 23 in the Walls 3 are suitably packed for preventing the escape of steam or pressure from the pressure cooker. Each yoke I9 is slidable on its shaft 2l to allow slight play or movement of the door I towards to and away from the opening 9.

The inner edges of the anges II around the opening Q are formed of about the same shape as the outline of the door I5. In the present illustrative embodiment the horizontal edges of the flanges I I at the opening 9 are straight, While the vertical edges of the same are arcuate, and of the same radius as the radius of the cylindrical segment forming the door I6. In order to provide a compressible contact between the inner` edges of the flanges i I and the door I6, a cornpressible packing is provided between the inner edges of the flanges Ii and the outer surface of the door I6. This packing 2P, in the form shown in Fig. 5, is held in retainer rims Zii mounted on the anges I I so as to hold the packing 24 around the sides of the opening 3. In the form shown in Fig. 8 thepacking strips E@ arel mounted ircre tainer grooves 2?' along the outer edges of.' the door I 6.

The door structure i #i is adjustable radially with; respect to the axis of the pivot shafts 2 I. In other words the yokes IS are slidable on the shaft 2i" toward and away from the opening 3.. A. coil spring 23 is anchored at one end thereof to the shaft 2I and at its other end to the` cross-barZS', which latter is suitably engaged with theadjacent arms l1 so that the action of the coil springs 23 normally pulls the door iii away from the opening 9. When the door IS closed the steam pres.- sure inthe casing I acts upon the concave side of thedoor IS and presses the door Ii against the packing strips. When the pressure is released or a slight vacuum is created in the casing I', then the atmospheric pressure as well as the action of the spring 2S shifts the door IS away from the packing strips 24. Atmospheric air thus admitted into the. casing l. equalizes the pressure. on the opposite sides ofthe door I6 and thereby facili'- tates the turning of the door.

The door I6 is held in position by a clamping devicedenoted in itsentirety by thev numeral" 31. This clamping device includes a pivoted clamp bar $2. This bar 32 in the present arrangement.

ispivoted at its lower end and has its upperend;

bearing against the front wall I' above the open'- i'ng 9. Through a centralhub 33 of' the clampbar 3E is extended, a threaded shaft 34 on the, inner end of which is a hook 36. for engagement with acrossbar 3'! in arecess 38 formed in aboutA the center of the door I5`. AA hand wheel 39' is threadedly engaged with the threaded shaft. 34 and' operates as a tightening nut. bearing against the, outer surface of the clamp hub 33..V When the door I is inthe closing position, the hook.` 3G is engaged with the cross bar 3l and the hand'wheel 39'is tightened, hearing against the clamp bar 33' and tightly pulling the` door It against the pack ing strips 263. In order torelease the door IIS` the. hand wheel 39 is loosened andthe hook. 35 isdisengaged' froml the cross bar 3l' of the; door' I G. Then the clamp bar 32 can be. swung into an out' ofthe way position,.perrnitting access through the opening 9. The hole fil in the hub 33 ofthe clamp bar 32. is tapered and is larger than the, threaded shaft 34 so as. to allow the swinging-of the hook 35. into and out of engagement with the cross; bar 37..

A steam intake l2 is provided: in the herein illustration,v at the, lower portion of the front wall l' near one ofthe side Walls 3 of the box I. The intake 42 is controlledby a suitable intake valve' 43, The exhaust passage S is controlled by suitable exhaust valve 114.. The operation ofthe intake valve 43. and of the. exhaust valve 44' is coordinated, andthe operation of both. valves is also coordinated with the operation ofthe clamping bar 3,27. The coordination between the intake valve iiand the exhaustvalve is for the purpose of: simultaneously adjusting both valves to: certain: c enditions inthe operation of the-pressurecooker.. InV the present. illustration the valves. 43 and. 44j areofthecockvalve type, wherein the cockvalves.

all andr lil., respectively,l have their. passages. 43

and 49 at right angles to one another. In other Words as shown in Fig. 6 when the cock valve 4S of the intake valve t3 is fully open, then the cock valve 49 of the exhaust valve 4g is fully closed. Relative movement of the valves is accomplished by the arrangement of valve levers 5I and 52, respectively operating the cock valves i6 and 4l. For simultaneous operation the valve levers 5I and; 52- are4 connected by.' a link 53. The valve lever 5t o n the intake valve 123 is. provided with a handle 54 for the manipulation of the valves. When the handle 5d is pulled forward into the position shown in the lowest pressure cooker unit inFi'g; 4", then the intake valve i3 is fully closed, andthe eXhaustvalve is fully open. This is the position where the door of the pressure cooker cany be opened andy shut at will and food can be placedl into or removed from the casing I. After the door I 5 is closed and clamped in position, the handle lever 54 is moved into the position shown in theI middle unitl in Fig. 4 and inFig. '7. In this intermediate position both the intake valve and the'v exhaust valve are partly open. rlhus in the beginning ofthe operation steam is admitted into.

the casing I and the trapped air is rapidly ex'- pelled from the casing I. Thereafter, the handle 512 is movedVH into the position shown on the top unitv of Fig, 4'- and'` Fig. 6, in which position the.

intake valve 43 is fullyv open and the exhaust valve 44" isN f'ully closed allowingY the building up of a suitable steam pressure in the pressurecooker.

Thef operation of' thev valves' 't3V and 44 is also coordinated with the opening of the clamping de viceY 3|. As shownl in Fig. 3, theclampingbar 32' is pivoted at its' lower end on a cross shaft 55. This cross shaft 53 is suitably journalled on the front wall I of the casing I and it operates also as the valve shaft for the turning, of the intakev valvev 43. The turning movement of the. shaft 55 is transmitted through the valve levers 5I and 52 andV the` link 53` to the exhaust valve 44. In the pivoted end ofi the clamping bar 32 is a slot lwhich'is concentricwith the shaft 53, Anabutmenti screw 581 extends from the shaft 55 and` through: said slot 57. The abutment screw. 53. extends horizontally" and adjacent the upper end of theV slot 57l whenY theV intake valve 53 is open.`

When the clamping bar 32 is opened the upper end of the slot 51 abuts against the screw 58 andv turns the` shaft 53 in a counter-clockwise direction as shown in Fig, 3, thereby shutting off the'val've'j 43. In this manner the opening of the door while the steam is still on is prevented, because the turning of the clamping bar 32 automaticailyshuts olf the steam. Thereverse operation protects against the turning on of" the steam without clamping the door, namely, when the dicated at 62.

In operation. the clamping device 3i is4 opened andthe door I3 is swung into the upwardV opening position above the 'center of the pivot shaft 2l audit is. held. in that. positionby thel engagement. of the. handle. 22 with theabutment 2li. A.

tray or vessel. containing, the food, to be cookedl is then inserted through the opening 9 and placed upon the perforated shelf I2. During this time the lever 54 is in the position shown in the lowest unit in Fig. 4, and the intake valve i3 is closed and the exhaust valve 44 is open. After the food is in the casing I, the operator, by turning the handle 22, swings the door I6 down into the` closed position shown in Fig. 5. The friction in the packings 24 as well as the action of the coil spring 28 holds this balanced door in alignment with the opening 9. Then the clamp bar 32 is swung into the clamping position shown in Fig. 5, the hook 38 of the shaft 34 is engaged with the cross bar 31 in the door IE5, and the hand wheel 39 is tightened so as to center the door I E and draw it against the compressible packing strips 24. Then the Valve lever 54 is turned to the position shown in the second unit in Fig. 4, and the valves are thus turned into the position illustrated in Fig. 7, namely, both the intake and exhaust valves are partly open. Steam now is admitted into the casing I for expelling the air through the partly open exhaust valve 44. Then the valve lever 54 is turned into thevertical position shown in the top unit of Fig. 4 and this will completely open the intake valve 43 and close the exhaust valve 44 as illustrated in Fig. 6. Steam is now freely admitted into the casing I under cooking pressure. This steam pressure in the casing I bears against the concave side of the door I6 and presses the door against the packing strips 24 for tight sealing of the pressure cooker. The food is left in the cooker for a desired period. Then the handle 54 is turned into the initial position, closing the intake valve and opening the exhaust valve. This assists in quickly exhausting the steam pressure from the cooker. Then the clamping device 3i is loosened, disengaged from the door, and finally the door is swung again into open position. The door can be easily opened at this time because there is no steam pressure behind the door I and the coil spring 28 pulls the door away from the inner ends of the flanges II. The cooked food can now be removed and the pressure cooker is ready for another operation. In the event the Ioperator does not shut 01T the steam, and attempts to open the door, then the swinging of the clamping bar 32 downwardly operates to automatically shut oi the steam as the clamping bar 32 is swung open, thereby reducing the steam pressure behind the door and allowing the exhaust of the steam from the cooker before the door is opened.

The pressure cooker herein described may be made in single units or in multiple units. The features of this invention may be incorporated in pressure cookers which are heated on a stove, or in units where outside steam supply is provided, or in units where a steam generator is furnished with the pressure cooker.

I claim:

l. In a pressure cooker a box having an inlet opening on one side thereof, an arcuate door in the inside of said box, an arcuate seat on the inside of said opening conforming to the face of said door, the concave face of said arcuate door facing inwardly from the box to be pressed by the pressure in the box and toward said seat. and mounting means inside of the box to swingably support said door and to transmit swinging movement to said door toward to and away from said opening, said door mounting means including pivot shafts journaled in the box, mounting arms extended from the concave side of said door being slidably held on said pivot shafts and for rotation with said pivot shafts, resilient elements connected to said pivot shafts and to said arms to normally pull said arms and said door away from said opening and towards said pivot shaft, and a handleon the outside of one of said pivot shafts for the manipulation of said door.

2. In a pressure cooker of the character described, a box, said box having an inlet opening through one side thereof, a door of arcuate cross section inside of said box, a seat for the door formed inside of said opening and conforming to the convex outline of said door, the concave side of said door facing inwardly of the box arms extended from the concave side of said door, pivoting means journaled in the box substantially centrally to the arc of said door cross section hubs formed on said arms and connected for rotation with said pivoting means, said hubs being slidable relatively to said pivoting means transversely to the pivot axis, packing strips between said seat and said door, and means outside of the box for turning said pivoting means and said door.

3. In a pressure cooker of the character described, a box, said box having an inlet opening through one side thereof, a door of arcuate cross section inside of said box, a seat for the door formed inside of said opening and conforming to the convex outline of said door, the concave side of said door facing inwardly of the box arms extendedvfrom the concave side of said door, pivoting means ,iournaled in the box substantially centrally to the arc of said door cross section, hubs formed on said arms and connected for rotation with said pivoting means, said hubs eing slidable relatively to said pivoting means transversely to the pivot axis, packing strips between said seat and said door, and means outside of the box for turning said pivoting means and said door, a clamping element pivoted on the outside of said box and swingable across said opening at will, a hook on said clamping element, an engagement member on said door to be engaged by said hook, and means to draw said hook towards said clamping element for clamping the door in closed position.

4. In a pressure cooker of the character described, a box. said box having an inlet opening through o-ne side thereof, a door of arcuate cross section inside of said box, a seat for the door formed inside of said opening and conforming to the convex outline of said door, the concave side of said door facing inwardly of the box arms extended from the concave side of said door, pivoting means journaled in the box sub-` stantially centrally to the arc of said door cross section, hubs formed on said arms and connected for rotation with said pivoting means, said hubs being slidable relatively to said pivoting means transversely to the pivot axis, packing strips between said seat and said door, and means outside of the box for turning said pivoting means and said door, the arc of said door and its radial spacing from said pivot axis being smaller than the distance of the pivot axis from another side of the box to permit the door to be swung into out-of-way position, and resilient elements connected between said pivoting means and said arms for normally urging said door towards said pivot axis.

WILLIAM A. PLEDGER..

(References on following page) REFERENCES; CITED Thev following references areof recordl in the le of this patent:

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